820001999 has 4 divisors (see below), whose sum is σ = 848277960. Its totient is φ = 791726040.

The previous prime is 820001993. The next prime is 820002011. The reversal of 820001999 is 999100028.

820001999 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 820001999 - 2⁴ = 820001983 is a prime.

It is a Duffinian number.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820001993) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14137937 + ... + 14137994.

It is an arithmetic number, because the mean of its divisors is an integer number (212069490).

Almost surely, 2^820001999 is an apocalyptic number.

820001999 is a deficient number, since it is larger than the sum of its proper divisors (28275961).

820001999 is a wasteful number, since it uses less digits than its factorization.

820001999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28275960.

The product of its (nonzero) digits is 11664, while the sum is 38.

The square root of 820001999 is about 28635.6770305855. The cubic root of 820001999 is about 935.9909229006.

The spelling of 820001999 in words is "eight hundred twenty million, one thousand, nine hundred ninety-nine".